Influence of processing on fruit health potential: an exhaustive review of scientific evidence
Résumé
Background and rationale
Fruits are protective for health. However, is this true whatever the degree of processing? Indeed, some studies suggest that the protective effect of food depends on the degree of processing [1]. Our objective was therefore to examine: 1) meta-analyses linking fruit consumption and risks of chronic diseases/metabolic deregulations according to fruit degree of processing; 2) the mechanisms underlying the potential "processing" effects with a focus on nutritional density, and the antioxidant, satietogenic, alkalizing and glycemic potentials.
Materials & method
Systematic review of meta-analyses: articles were selected until June 2018 [2]. The keywords notably included ‘type of publication’, ‘fruit products’, ‘chronic diseases’ and ‘their risk factors’. Study was carried out according to PRISMA method. Our research identified 189 meta-analyzes, of which 10 met our inclusion criteria [2]. Narrative review of potential mechanisms underlying the “processing effect”: articles were selected until July 2018 [3]. The keywords notably included ‘fruit’, ‘processes’, and ‘nutritional properties’.
Main results & Discussion
The umbrella review of meta-analyses showed a technological gradient of fruit health potential with respect to the risks of chronic diseases and their risk factors. Fresh and dried fruits are neutral or protective, 100% fruit juices are rather neutral with also protective and deleterious effects depending on diseases, and canned fruits/fruit juices with added sugars were associated with mortality and type 2 diabetes, respectively. Secondly, we observed that the more fruits are processed, the lower their alkalizing, antioxidant and satietogenic potentials. With regard to the glycemic index, the results are more difficult to interpret, fruits being important sources of fructose with a very low glycemic index. Overall, destructuring of fruit fibrous matrix by thermal and mechanical treatments, combined with added sugars, constitute the treatments, which most degrade the nutritional quality of the fruits, through diluting the nutritional density and reducing the “matrix” effect.
Conclusion
Raw fresh fruits and dried fruits have the best health potential. Our results confirm the need to take into account the degree of processing in the next epidemiological and randomized controlled intervention studies, in order to adapt the official recommendations relating to fruit consumption.
References
1. Fardet, A. (2018). Advances in Food and Nutrition Research, 85:79-121.
2. Fardet, A., Richonnet C. et al. (2019). Nutrition Reviews, 2019. 77(6):376-387.
3. Fardet, A. and Richonnet C. (2019). Critical Reviews in Food Science and Nutrition, 2019. DOI: 10.1080/10408398